Automatic signaling system for telephone-exchanges.



No. 683,569. Patented Oct. 1, 19m.

J. L. MGDUARRIE. AUTOMATIC SIGNALING SYSTEM FOR TELEPHONE EXCHANGES.

,(Application filed. Jan. 26, 1901.)

.(No Model.)

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UNITED STATES PATENT OFFICE.

JAMES L. MCQUARRIE, OF CHICAGO, ILLINOIS, ASSIGNO R TO THE XVESTERNELECTRIC COMPANY, OF SAME PLACE.

AUTOMATIC SIGNALING SYSTEM FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 683,569, dated October1, 1901.

Application filed January 26, 1901. Serial No. 44,906. (No model.)

To all whom it may concern.-

Be it known that I, JAMES L. MCQUARRIE, a citizen of the United-States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvementin Automatic SignalingSystems for Telephone-Exchanges, (Case No. 13,) of which the followingis a full, clear, concise, and exact description.

My invention relates to a telephone-exchange system, and concerns moreparticularly the operators central-oflice apparatus for makingconnections between two telephone-lines, my object being to substituteautomatic devices for doing a share of the work which has hitherto beendone personally by the operator, and so to economize the operators timeand enable her to handle a much larger number of connections than hashitherto been possible. Y

\Vith telephonecxchange systems at present in use the operator finds itnecessary to ring the called party a definite number of times or adefinite length of time, and if no response is had she must connect hertelephone with the calling-line and report to the calling subscriberthat no answer has been made to her signal. Usually the calling partyasks that the subscriber wanted be run g again,

being the insertion of the calling-plug in the jack of the called line.

The invention may be generally described as comprising a source ofpeculiar oi characteristic signaling-current, (which may be aphonograph-transmitter, a musical-tone-producing transmitter, or thelike,) a switch for connecting the same with the calling-line, a timedevice operated or set in operation during the applicationof-ringing-current to the called line, and means controlled by the timedevice for actuating said switch. In the preferred embodiment of myinvention the ringan electromagnetic step-by-step device responsive tothe intermittently-applied ring-. ing-current advances a predeterminednumber of steps and then actuates a switch which disconnects the ringingcurrent from the called line and connects the peculiar signaling-currentwith the calling-line. The call-. ing subscriber listening in histelephone thus hears after a given time either spoken words from aphonograph, such as They dont an,- swer, or a peculiar hum or tone,which he recognizes as meaning that the called party has not responded.He will then hang up his telephone, and the usual supervisory signallampat the central office will be lighted, giving the operator the signal todisconnect.

The apparatus of my invention will be useful either at a trunking-boardor B posiing-current is periodically interrupted, and

tion, where calls are received over trunklines from distant boards, or'at an answering-board or A operators position, where:

the call comes directly from the subscriber..

I will describe my invention particularly by reference to theaccompanying drawing,

which is a diagram illustrating two telephone-lines extending from asubstation to a central office, with the operators apparatus forconnecting the lines, equipped with the signaling apparatus of myinvention, and the features which I regard as new will be pointed out inthe appended claims.

The two telephone-lines illustrated, ex-

tending from substations A and B to the central office C, are equippedwith the usual substation and central-office apparatus, the system beingof a well-known type, in which a central source of current is connectedwithv all the lines and each line is provided with a line-relaycontrolling a subsidiary signal at the central office, responsive to theflow of current in the line, which is determined by the telephone-switchat the substation. The

central source of current and the line-relay- The apparatus of myinvention is intended signal-lamps c d and resistances 0 d moreparticularly for application to the operators plug-circuit, as shown inthe diagram. The plug-circuit, generally considered, is of the usualtype for systems of the character described, and consists of ananswering-plug c and a calling-plug cl, the tip and ring contacts ofeach plug being united with the corresponding contacts of its mate bylink conductors 1 2 of the plug-circuit, with arepeating-coil interposedin said link conductors and a central battery gin a bridge of said linkconductors between the windings of the repeating-coil. A supervisoryrelay-magnet c is associated with the answering-plug and connected inthe circuit of the conductor 2 between the central battery g and saidansweringplug, and similarly a supervisory relay-magnet f. is includedin the portion of conductor 2 leading from the battery to thecalling-plug d. One pole ofthe battery g is grounded, and the thirdcontacts of the plugs c and d, which are adapted to engage the testringsof the jacks, are connected with the free pole of said battery byconductors 3 4, respectively, which include the subsidiary The conductor2 of the plug-circuit between the battery 9 and the calling-plug is inthe normal or idle position of the plugs interrupted at the contacts ofa relay h, the end leading to the ring-contact of the plug beingconnected to the armature h of said relay and theother end leading tothe battery being connected to the front contact of said armature. Therelay h has two windings. One of said windings h is included in a shunt5 about the signal-lamp d, which shunt includes and is controlled by thearmature and front contact of the supervisory relayf, and the otherwinding k is included in a conductor 6, which is connected in parallelor shunt with the resistance 61 and includes and is controlled by thearmature h and its front contact of the relay hitself. The conductor 2,leading to the calling-plug, is normally connected by way of the backcontact of relayarmature h and a conductor 7, including certain otherapparatus, presently to be described, with the contact-plate t" of acontinuously-rotating commutator or interrupter 't'. The contact-plate itakes up half the periphery of the commutator and the other half is ofinsulating material. Two contact-brushes t i bear upon opposite sides ofthe commutator, one of said brushes being connected to a groundedbattery and the other being connected to a grounded generator ofringingcurrent 7c. The conductor 7 includes the winding ofa magnet Z,which controls a stepby step mechanism, hereinafter to be described, andincludes and is controlled by a switch-lever m and its front contact,said lever being operated by the step-by-step mechanism aforesaid. A camm is mounted upon a rotatable shaft u, said cam being circular exceptfor two projections or lugs m m at diametrically opposite points uponits periphery. Theswitch-leverm andasimilarswitch lever m rest uponopposite sides of the pe riphery of the cam m, the ends of said leversbeing diametrically opposite one another and being yieldingly held downto the surface of the cam by springs. The switch-lever m normally restsagainst its contact-point,which is connected to the interrupter orcommutator 't', and is separated from said contact-point when theswitch-lever rides up upon one of the lugs m of the cam. The otherswitch=v lever m has a contact-point from which it is normallyseparated, but with which it ongages when moved by one of the lugs m ofthe'cam. This contact-point is connected to the limb Zof theplug-circuit between the battery g and the calling-plug, and the lever mis connected to a grounded source 8 of specialized current, such as aphonograph-transmitter or an interrupter which will produce adistinctive hum or tone.

The shaft or, which carries the cam m, is mounted to rotate in bearingsand carries a ratchet-wheel 0. A spiral spring a, encircling the shaft,tends tokeep the same in the position illustratedthat is, with the lugsm m abutting against the ends of the levers m m Two pawls pp engage theratchet-wheel 0 upon opposite sides. One of these pawls p is attached tothe armature Z of the electromagnet l and is adapted to be pressedagainst the ratchet-wheel 0 by a spring g carried by the armature q ofan electromagnet q. hen the magnet Z attracts its armature, theratchet-wheel will therefore be rotated one step. The other pawl 19 iscarried by a fiat-spring extension of another armature q ot' the magnetq and is adapted merely to hold the ratchet-wheel in the positions towhich it may be advanced by the other pawl worked by the magnet I. Whenthe magnet q is denergized, its armatures fall back, thus removing thepawls p 19 from engagement with the ratchet, whereupon the shaft n beingreleased is rotated back to its original position. The magnet qisincluded in a shunt 8 about the supervisory lamp 0 of theanswering-plug and is controlled by the armature of the supervisoryrelay e, which is responsive to the flow of current in the callingline.The armature q of relay q and aback contact for said armature control ashuntpath 9 about the armature 7L and its front contactin other words,the contacts controlled by armatures h and g are in multiple, and theclosure of either completes the circuit through the retaining-winding72/3 of magnet h.

The operation of the system is as follows: Assuming that a call has beentransmitted from substation A in the usual manner and answered by theoperator inserting her plug in the spring-jack, connecting her telephonein circuit and ascertaining the number of the subscriber wanted, aftermaking the usual busy test the operator simply inserts the calling-plugd in the springjack of the line with which connection is desired. Thisis all the work that is required of her until the signal is made to takedown the connection. When the calling-plug isinserted, the called-partystelephone being on its hook, thesupervisory relayfisinert. Consequentlymagnet h is also inert, and the ring of the calling-plug is thusconnected, by wayof armature h and its back-contact winding of magnet Zand switch-lever m and its normal resting-contact, with thecontact-segment 'i of the commutator or interrupter 2'. As thecommutator rotates ringing-current is intermittently applied to theline, a steady current being substituted for the ringing-cu rrent duringthe intermissions. The magnet Z is responsive to the alternatingringing-current; but the magnet of the supervisory relay f is not. Thetelephone-receiver being on the hook at the called station, noreturn-path is provided for the steady current, so that neither of themagnets just mentioned is affected by such current until the subscriberhas answered the call by removing his telephone from thehook,andsoclosing thecircuit. At each application of ringing-current to the lineby the commutator i, therefore, the magnet Z will be excited and willattract its armature, and in the intermissions the magnet becomes inertand allows its armature to fall back. The magnet g at this time isexcited, because the shunt-circuit controlled by the supervisoryrelayeofthe calling-lineis closed, (the calling-subscribe1"s telephone being offthe hook,) so that the pawls p p are yieldingly held against theratchet-wheel 0. Each time the magnet Z draws up its armature,therefore, the shaft 91 will be held by the pawl 13 in the position towhich it is advanced. 1f the called subscriber does not respond, thecommutator will continue to apply the ringing-current intermittently tohis line until the step-by-step mechanism has advanced the cam 'msufficiently to engage the lugs m m with the switch-levers m m As theswitchlever m rides up on one of the lugs m of the cam it breaks thecircuit of conductor 7, leading to the commutator and the sources ofcurrent connected therewith,and simultaneously the switch-lever m ispushed into engagement with its outer contact. The effect, therefore, isto stop the application of ringing-current to the called line and toconnect the source' of peculiar or specialized current- 5 with theconductorl of the plug-circuit. Current from the source 8 thus flows toground through a winding of the repeating coil, whereby a correspondingcurrent is induced in the other windings of the repeating-coil, whichflows back to the calling-station and produces an audible signal in thetelephone of the subscriber who is listening for a response to his call.This signal may be either spoken words from a phonograph or a hum ortone or any other audible .signal which the calling subscriber willrecognize as meaning that no response is had from the called station.The

calling party upon hearing the special dontanswer signal knows that itwill be of no use to signal the called party any longer and replaces histelephone on its hook, thus bringing about the illumination of hissupervisory lamp 0 Since the supervisory lamp d of the called party isstill lighted, the illumination of both lamps constitutes a signal tothe operator to disconnect. At the same time the magnet q is deprived ofcurrent by the opening of the shunt S and allows its armature to fallback, thus releasingthe ratchetwheel 0. The shaft n is thereforereturned to its initial position by the coiled spring at. The armature qin falling back closes the circuit through the winding 72 0f magneth,which in drawing up its armatures permanently cuts off theringing-current from the called line. In ordinary cases, however, thecalled subscriber will answer and in taking his telephone for use willclose a bridge of his linecircuit, whereupon the supervisory relay f atthe central office will respond to the flow of current in the line andclose the shunt 5, which includes the winding 7L2 of magnet h. Thismagnet in drawing up its armatures cuts off the ringing-current andestablishes the talking-circuit through the repeating-coil. Circuitthrough the retaining-winding 71 15 also closed by armature 72%, so thatthe magnet h is now independent of the telephone-switch at the calledstation and maintains the ordinary talking-circuit connections as longas the plug remains in the springjack.

It will be apparent that my invention is capable of being applied to thereceiving end of a trunk-line to signal back to the answering board, andwhere in the claims I use the term calling-line I do not mean torestrict myself to a subscribers line. In fact, my invention is capableof application to telephone systems of various kinds, and thearrangement shown in the drawings may be modified within comparativelywide limits and still make use of the new ideas which I have herein setforth. I do not therefore wish to be understood as limiting myself tothe precise apparatus and circuits illustrated; but,

Having described the preferred embodiment of my invention, I claim asnew, and desire to secure by Letters Patent, the following:

1. The combination with a calling and a called telephone-line and meansat a central office for uniting them, of an automatic ringing device atthe central office for sending signaling-current over the called line, asource of distinctive signaling-current, a switch for connecting thesame with the calling-line, a time device set in operationsimultaneously with the automatic ringing device, and means controlledby said time device for actuating said switch, whereby the calling partyis antomatically notified when the called station has been signaled agiven time, substantially as set forth.

2. The combination with a calling and a called telephone-line and meansat a central I &

office for uniting them, of an automatic ringing device at the centraloffice for signaling the called station, a source of peculiar-orcharacteristic signaling-current, a switch for disconnectingtheringing-current from thecalled line and applying the peculiarsignaling-current to the calling-line, and an electrical device operatedby the flow of ringing-current in the called line, for bringing aboutthe operation of said switch, whereby ringing-current is automaticallyapplied to the called line for a given time and then stopped, and asignal transmitted to the calling-station, substantially as set forth.

3. The combination with a calling and a called line, and means at acentral office for uniting them, of a source of ringing-current and aringing device at the central office for connecting the same with thecalled line, means controlled through the agency of a switch at thecalled station for disconnecting the ringing-currenl, a time device setin operation when ringing-current is applied to the called line, asource of characteristic signaling-current and a switch for connectingthe same with the calling-line, controlled by said time device, wherebythe called party is automatically signaled for a definite time and, uponhis failure to respond, a report to that elfect automatically made tothe calling party, substantially as set forth.

4. The combination with a telephone-line extending to a central office,and means for there connecting it with a second or called line, of asource of ringingcurrent and means for connecting the same with thecalled line to signal the called party, means at the central office,under the electrical control of the called party for disconnecting thesignalingcurrent'from the line, a source of characteristicsignaling-current, and a switch for applying the same to thefirst-mentioned or calling line, and a time device for operating saidswitch, said time device being controlled by the flow of ringing-currentin the called line, substantially as set forth.

5. The combination with a calling and a called telephone-line, and meansat a central office for uniting them, of a source of ring ing-currentand means for automatically applying the same to the called line, meansat the central office, under the electrical control of a switch at thecalled station, for disconnecting the ,source of ringing-current, a

source of peculiar or characteristic signalingcurrent, and an automaticswitch for applying the same to the calling-line, an automaticinterrupter for intermittently disconnecting the ringing-current fromthe called line, and a step-by-step device operated by the intermittentflow of ringing-current, controlling said automatic switch, whereby thecalled party is automatically signaled for a given time, and a signalthen transmitted to the calling party indicating that there has been noresponse, substantially as set forth.

6. The combination with a calling and a called telephone-line and meansat a central office for uniting them, of a source of ringing-current andan automatic ringing device for applying the same to the called line,means controlled through the agency of a switch at the called stationfor disconnecting, the source of ringing-current, a source of currentconnected with the calling-line,means at the substation of thecalling-line for de termining the flow of current therein, andelectromagnetic mechanism controlled by the flow of current in thecalling-line, for disconnecting the ringing-current from the calledline, substantially as set forth.

'7. The combination with a calling and a called telephone-line and meansat a central office for uniting them, of a source of ringing-current andmeans for automatically applying the same to the called line, means atthe central office under the electrical control of a switch at thecalled station, for stopping the flow of the ringingcurrent, a source ofpeculiar or characteristic signaling-current, a switch for applying thesame to the calling-line and disconnecting the ringingcurrent from thecalled line, an instrument in the calling-line responsive to suchpeculiar signaling-current, a rotatable cam for actuating the switchlast mentioned, a device for V intermittently interrupting the flow ofringing-current in the called line, and an electromagnetic step-by-stepdevice responsive to the intermittently-interrupted ringing-current, forcontrolling the rotation of the aforesaid cam, substantially as setforth.

In witness whereof I hereunto subscribemy name this 4th day of December,A. D.'1900.

JAMES L. MCQUARRIE. \Vitnesses:

ELLA EDLER, ADELL HOCKETT.

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